Converter steelmaking which uses, as a raw material, solid iron-containing cold material such as granular pig iron, mold pig iron and scrap of ironworks has been known. In the converter steelmaking, dust generated in an exclusive converter for melting and an exclusive converter for refining and containing iron as a main component is recycled.
In order to use such dust as a raw material, collected dust and a reducing material are mixed and then kneaded, they are subjected to an agglomeration process to be agglomerate, and then the agglomerate is reduced to produce direct reduced iron. Since a property of the direct reduced iron is influenced by a property of the agglomerate, various studies on the agglomerate have been conducted.
For example, the following Patent Document 1 discloses a method of obtaining agglomerate which is hard to break in an operation of a rotary hearth furnace as a direct reduction furnace by mixing and kneading a raw material of the agglomerate in a vibration mill and covering a surface of the raw material of the agglomerate with moisture.
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2002-167624